1. Field of the Invention
This invention relates to translation apparatus.
This invention has particular reference to translation apparatus for use on milling machines and for illustrative purposes reference will be made hereinafter to such application. However aspects of this invention may have general application to monitoring cutting tool position in metal cutting machines such as milling machines and lathes. This invention also relates to cutting machines and, in particular, metal cutting machines incorporating such translation apparatus.
2. Description of the Prior Art
Frequently, during machining operations, an operator will utilize a variety of cutting tools to perform various operations on a workpiece. Typically, such actions necessitate the operator resetting the machine each time a tool is changed so that a datum position of a current tool may be established, whereby the operator may control the cutting tool position and thus a depth of cut. Where frequent tool chances are made, this becomes a time consuming and tiresome task, with increased potential for operator error.
In more recent times operators of such machines have benefited from use of digital readout displays providing accurate directly readable information as to the relative positions of the machine components. Such devices commonly include a digital readout assembly having a measuring scale fixed to the main frame of the machine, such as a column of a milling machine and disposed parallel to the movement to be monitored, and an associated reader head fixed to the adjacent machine component which moves relative to the main frame, such as a knee of a milling machine which is slidable along vertically extending slides on a column and supports a table or workpiece support.
In this manner, relative movement of the knee along vertically extending slides is monitored on the digital readout display. Such displays typically have a keypad for selecting their operating mode, such as for selecting zero positions of the knee relative to the column while others have a facility for inputting and selecting zero positions for several different length tools.
In milling machines, the cutting tool is attached to a quill spindle which may be manually advanced to engage the tool with a workpiece. A vertical scale is provided on the quill head whereby an operator may monitor the position of the quill head spindle relative to the quill head and thus deduce the depth of cut or position of the cutting tool relative to the workpiece for the mounted cutting tool.
It is possible to support a further digital readout scale and reader head on the quill head so that the vertical position of the quill spindle relative to the quill head may be readily monitored and displayed. Unfortunately, such arrangements are cumbersome and do not provide an instant positional reading of the cutting tool relative to the workpiece. Additionally, the provision of two digital readout scales and reader heads also involves additional costs and causes operator access limitations.